The death of a boy with Duchenne muscular dystrophy, tied to a gene therapy, is above all a tragedy. But it is also undermining investor confidence in the company that makes it.

Another person treated with Elevidys suffered acute liver failure, leading Sarepta to discontinue treatment in certain patients while it evaluates new safety precautions.

Duchenne muscular dystrophy patient died after being treated with the gene therapy delandistrogene moxeparvovec (Elevidys), Sarepta Therapeutics said Sunday. Like the first case reported, this patient developed acute liver failure (ALF) that resulted in death.